Metering and mixing valves are essential in many uses, in home showers, in industrial processes, and in scientific experimentation. Each variable-flow valve has a maximum flow rate at whatever head pressure it is expected to operate, but desired ranges of flow rates may occupy only a lower part of the valve flow capability and hence may be conducive to careless or even intentional wastage of fluid.
Various metering and mixing valves appear in U.S. Pat. Nos., such as Moen 3,592,229; Redman 4,263,940; Hammett et al. 5,322,645; and Anwaerter et al. 5,697,554. In view of inherent limits on maximum flow in substantially all valve designs, those inventors' principal objectives did not include intentional or readily adjustable maximum flow limitation, and their respective contributions differed also.
Despite the foregoing and other examples of meritorious valves, a need remains for built-in control of maximum flow rate, readily pre-settable but precluding resetting by uninformed users.